1. Field of the Invention
This invention relates to ion generators and, more particularly, to a device and related method for electrolytically generating halogen ions from a salt halide solution for use as a biocide in a swimming pool.
2. Background Information
Traditionally, chemicals such as calcium hypochloride have been added to water supplies to serve as a "biocide", defined herein as an agent capable of eliminating as a health risk algae, bacteria and viruses. However, using such chemicals is expensive, represents serious shipping, storage and safety concerns, and results in uneven concentrations and dissipated effectiveness over time. See, e.g., U.S. Pat. Nos. 4,790,923 and 4,100,052.
Biocidal activity can also be accomplished by using electrolysis to produce sufficient ions in solution to disrupt cell membranes or protein sheaths by rapid chemical interaction. In this regard, ion generators, are known which are capable of creating ions from salt solutions for use in, e.g., a swimming pool filtration system. An example of such an ion generator follows.
U.S. Pat. No. 4,100,052 describes a generator of chlorine ions from a chloride salt/water solution. The generator uses electrodes in the form of platinum coated plates which are parallel to the salt/water solution flow. The plates are about 0.02-0.06 inch thick and spaced about 0.025-0.5 inch apart. The ion generator is used in a swimming pool water filtration system or to treat sewage or cooling tower water.
The drawbacks of conventional ion generators follow.
These generators usually operate by electrolyzing a sodium chloride/water solution contained within a chamber, attracting positively charged sodium ions to a negatively charged cathode and attracting negatively charged chloride ions to a positively charged anode, thereby liberating chlorine gas at the anode. The chlorine gas is then used to chlorinate the water within a swimming pool, spa or the like. See U.S. Pat. Nos. 4,808,290, 4,997,540, and 4,328,084. However, chlorine gas is highly poisonous and excessive inhalation may cause death.
U.S. Pat. No. 4,808,290 provides a device which captures and passes the chlorine gas through a reaction column and cathode chamber. It would be preferable, however, to avoid altogether the production of chlorine gas.
Electrodes in the form of plates running parallel to the direction of flow of the salt/water solution are inefficient. That is, molecules that are ionized at the beginning of a first plate are attracted to a second opposite plate and may be neutralized before they pass beyond the end of the first plate, thereby wasting the electric current used to produce the ions.
The electrodes of conventional ion generators are relatively thick and are arranged in relatively widely spaced relation. This is not the most efficient configuration for ion generation, again because ion neutralization may occur.
Conventional ion generators also rely merely on normal water flow to pass over the electrodes. Due to this configuration, the ions formed tend to linger near the plates. As a result, the ions fail to enter the water supply in a timely manner and, therefore, do not fully serve their biocidal purpose.
Further, many of the conventional ion generating systems, and the related methods of use, such as described in the above-discussed U.S. Pat. No. 4,808,290, are either too expensive, complicated or cumbersome for widespread use with swimming pools, especially residential pools.
As discussed above, the prior art still does not teach an ion generator and method for ion generation which are capable of the most efficient production of halogen ions from a halide salt/water solution.